Radio apparatus



April 28, 1936- w CARLSON Re. 19,945

RADIO APPARATUS Original Filed May 23, 1927 Inventor;

Wendell L. Carlson,

' His Attorney.

Reissued Apr. 281936 UNITED STATES PATENT OFFICE No. 193,438, May 23, 1927. 'Application for reissue August 3, 1934. Serial No. 738,330

19 Claims. (Cl. 178-44) a My invention relates to radio apparatus, and has for its principal object the provision of an improved amplifying and detecting apparatus which may be readily adjusted to operate either 4andlarearrangedtobe'adjustedbyasingle control member ii. In order to ensure the proper relation between the capacities of the different tuning condensers, compensating condensers l3 and I! are connected in parallel with the 5 with a high degree of fidelity or with a high decondensers l2 and I3. 5

gree of selectivity. The transformer I is provided with a primary When broadcast stations are operated at frewinding l8 arranged to be connected to ground quencies spaced apartby kilocycles, it is diffleither through a lead 20 and a switch 2| or cult to operate receiving apparatus with high through lead l9 and switch 2| and with a sec- 10 quality and sharp selectivity without reverting to ondary winding comprising sections 22 and 23 10 single side band transmission. It is of course posbetween which are interposed a resistor 24. The sible to operate suchapparatus with a moderate output'circuit of the detector 5 is arranged to degree of adjacent channel selectivity and with be coupled to the circuit 2 through a transformer cutofl' on the higher modulation frequencies. 25-cor'nprising a secondary winding 26 and pri- Practical tests show that the best quality of recepmary windings 21 and 28. A switching device 23 15 tion is obtained with a high fidelity adjustment comprising movable contact members 30 and 3| for local reception and with a poor fidelity and is provided for controlling the connections of the high selectivity adjustment for distant reception resistor 24, the primary-circuit 21 and the primary through interference. In accordance with my incircuit 28 which is connected in series with a vention, the receiving apparatus is arranged to be resistor 33. As indicated more clearly in Fig. 2, 20

. readily changed from a condition of high fidelity the secondary windings are loosely coupled to with regard to the signals of a plurality of adiathe primary winding 21 and closely coupled to the cent frequency bands or channels toa condition primary winding 23. v x of high selectivity for distant reception through The switch 23 is operable to three difierent'po- 25 interference. sitions. Assuming this switch to be in its right 25 Myinvention will bebetter understood from the hand position, the resistor 24 is short circuited. following description when considered in connec-v the winding 28 and resistor 33 are open circuited, tion with the accompanying drawing and its scope and the apparatus is highly selective but operates will be pointed out in the appended claims. with poor fidelity due to attenuation of the higher Referring to the drawing. Fig. 1 is a wiring dia- -modulation side band frequencies. The fidelity 30 gram of a radio receiving apparatus wherein my of the apparatus is greatly increased by operating invention has been embodied; and Fig. 2 illusthe switch 23 to its illustrated position and contrates a coupling transformer constructed in acnecting the winding 21 in series with the winding cordance with my invention. 28 and resistor 33. Operation of the switch 29 36 The receiving apparatus illustrated by Fig. 1 to its left hand position removes the short circuitcomprises an antenna I and a circuit 2 which are from the resistor 24 and increases to some extent interconnected through a plurality of space disthe fidelity of the apparatus. charge devices comprising a pair of radio fre- It will of course be understood that connecting quency amplifiers 3' and 4 and a heterodyne dethe winding 23 in series with the winding 21 pro- 40 tector I coupled to the output circuit of a local duces a closer coupling between the output cir- 40 oscillation generator 3. The amplifier 3 is procuit of the detector 5 and the circuit 2 and broadv'lded with an input circuit coupled to the anens the frequency range of the receiving appatenna I through a transformer 1', with an output ratus, and that the eifect of the resistor 33 is to 4 5 circuit coupled to the input circuit of the amplifier equalize the response at different frequencies 4 through a transformer 3 and with a condenser Within the u I for neutralizing the capacity coupling between The embodiment of the invention illustrated its anode and grid. The amplifier 4 is likewise .anddescribed herein has been selected for the provided with an output circuit coupled to the purpose of clearly setting forth the principles ininput circuit of the detector 5 through a transvolved." It will be apparent however that the in- 50 former II, and with a condenser II for neutralizven n is susceptible f being m d to m ing the capacity between its grid and anode, the different conditions encountered in its use and Tuning condensers l2, l3 and I4 connected re- 1 therefore aim to cover by the appended claims spectively in the input circuits of the devices 3. all modifications within the true spirit and scope of my invention. 55

'WhatIcl'aimas newanddesiretosecureby LettersPatent of the United States is: y

l. The combination of a space discharge devic provided with an output circuit, a transformer comprising a secondary winding and two primary windings respectively loosely and closely coupled to said secondary winding, and switch means associated with said output circuit, said switch means in one position thereof completing said circuit through one of said primary windings and in another I position completing said circuit through both of said primary windings.

2. The combination of a space discharge device provided with an output circuit, a transformer comprising a secondary winding and two primary windings respectively loosely and closely coupled to said secondary winding, a resistor, and switch means associated with said circuit, said switch means in one position thereof completing said circuit through one of said primary windings and in another position completing said circuit through both of said primary windings and said resistor.

3. The combination of a space discharge device provided with an output circuit, a transformer comprising a secondary winding and two primary windings respectively loosely and closely coupled to said secondary winding, resistance means, and

switch means associated with said circuit, said switch means in one position thereof completing said circuit through said loosely coupled winding.

and in another position completing said circuit through both of said windings and said resistance means. j 4. The combination of a space discharge device provided with anoutput circuit, a transformer comprising a secondary winding and two primary windings respectively loosely and closely coupled to said secondary winding,-,and switchmeans associated with said output circuit, said switch means in one position thereof completing said circuit through said loosely coupled winding and in another position thereof connecting said primary windings to said circuit in series with one another.

5. An apparatus comprising an amplifier and a detector each provided with input and output circults, a resistor in the input circuit of the amplifier and a coupling impedance in the outputcircuit of the detector for decreasing the selectivity and increasing the fidelity of the apparatus, and switch means associated with said input circuit of said amplifier and with said output circuit of said detector, said switch means being operable to remove said resistor from the amplifier input circuit and said impedance from the detector output circuit, whereby said apparatus may be changed from a condition of high fidelity with de: creased selectivity'with regard to signals of a pinrality of adiacent frequency bands or channels to a condition of high selectivity and decrease of fidelity with regard to distant reception through interference.

6. An apparatus comprising an amplifier and a detector provided with input and output circuits, a transformer comprising a secondary winding and primary windings respectively loosely and closely coupled to said secondary winding, switch means associated with the output circuit of said detector, said switch means in one position thereof connecting one of said primary windings in the output circuit of the detector and in another position connecting all of said primary windings in the output circuit of said detector, and means laces for simultaneously tuning the input circuits of said amplifier and detector.

'1. An apparatus comprising an amplifier and a detector provided with input and output circuits, a transformer comprising a secondary winding and primary windings respectively loosely and closely coupled to said secondary wind- 8, switch means associated with the output circuit of said detector, said switch means in one position thereof connecting one of said primary windings in the output circuit of the detector and in another position connecting all of said primary windings in the output circuit of said detector, means for simultaneously tuning the input circuits of said amplifier and detector, and means connected to one of said input circuits for causing a predetermined relation to be maintained between the tuning of said input circuits.

8. An apparatus comprising an amplifier and a detector, said amplifier being provided with a tuned input circuit including a resistor and said detector being provided with an output circuit including a pair of primary windings and a resistor in series,said first-named resistor and one the apparatus, and switch means associated with said input circuit of said amplifier and with said output circuit of said detector, said switch means being operable to short circuit said first-named resistor and to open circuit said one of said primary windings simultaneously whereby the circuit constants'of said input circuit and of said output circuit may be changed simultaneously to change the operating characteristic of said apparatus from one of high fidelity to one of high selectivity.

9. The combination of a space discharge device provided with an output circuit, a transformer comprising a secondary winding and two primary windings respectively loosely and closely coupled to said secondary winding, and switch means associated with said output circuit, said switch means in one position thereof completing said circuit through said loosely coupled primary winding and in another position completing said circuit through both of said primary windings.

10. An apparatus comprising an amplifier and a detector provided with input, and output circuits, a transformer comprising a secondary winding and two primary windings respectively and coupling between said circuits. of means for narrowing the acceptance frequency band to provide high selectivity ton in said system and subsequently to widen the acceptance frequency band to provide high fidelity transmission in said system. said means including means for simultaneously changing the magnitude of the coupling between said circuits and the resistance of one of said circuits, said resistance after said change being of avalue suflicient sub stantially to equalize the of said system over said widened acceptance frequency band.

'12.!lhasystemfor ofabandof signals. the combination with two circuits one of which is adapted to include a resistance, and magnetic coupling between said circuits, of means for widening the acceptance frequency band to provide high fidelity transmission in said system said resistance having a value sufilcient sub-' stantiaily to equalize the response of said system over said widened acceptance frequency band.

13. In a system for transmitting a band of signals, the combination with two circuits one of which is adapted to include a resistance, and magnetic coupling between said circuits, of means for widening the acceptance frequency band to provide high fidelity transmission in said system after a period of operation characterized by a narrow acceptance frequency band providing high selectivity transmission in said system, said means including means for simultaneously increasing the degree of coupling between said circuits and for including said resistance in said one of the circuits, the value of 'said included resistance being sufiicient to insure that after said increase in the degree of said coupling the response of said 'system over said widened frequency band is substantially equalized.

14. The combination of a space discharge device, an output transformer for said discharge device comprising primary and secondary cir-' cuits, a plurality of windings for said trans former, a resistor, a first one of said windings being loosely coupled to a second one of said windings, a third one of said windings being closely coupled, to said second winding, and means operable to connect selectively said first one of said windings operatively in one of said circuits and to connect said first winding, said third winding and said resistor operatively in one of said circuits.

15. In a system for transmitting a band of signals of radio frequency, means to narrow the acceptance frequency band to provide high selectivity transmission in said system and subsequently to widen the acceptance frequency band to provide high fidelity transmission in said systcm, said means including two circuits and resistance means and further including means operable to couple said circuits loosely and operable subsequently to couple. said circuits closely and simultaneously to connect said resistance infrequency band at the will of the operator to provide high selectivity transmission in said system, and subsequently widening the acceptance frequency band and simultaneously substantially equalizing the response of said system over said widened acceptance frequency band at the will of the operator to provide high fidelity transmission in said system.

17. In a transmission system, the combination with two pairs of circuits, and coupling between the circuits of each pair, of means to provide high selectivity transmission in said system and subsequently to provide high fidelity transmission in said system, said means including means for simultaneously changing the magnitude of the coupling between the circuits of one of said pairs of circuits, the resistance of one of the circuits of said one of said pairs, and the resistance of one of the circuitsvof the other of said pairs.

18. In a system for transmitting a band of frequencies, the combination with a transformer, of

means for narrowing the acceptance frequency band to provide high selectivity transmission in said system and subsequently to widen the acceptance frequency band to provide high fidelity transmission in said system, said means including means for simultaneously changing the mag-, -nitude of the coupling in said transformer and the resistance of said transformer, said resist-' ance after said change being of a value sufilcient substantially to equalize the response of saidsystem over said widened acceptance frequency band. r

19. In a transmission system, the combination with two transformers, of means to provide high selectivity transmission in said system and subsequently to provide high fidelity transmission in said system, said means including means for simultaneously changing the magnitude of the coupling in one of said transformers, the resistance of said one of said transformers, andthe resistance of the other of said transformers.

WENDELL CARI-SON. 

